Changes in spontaneous and sensory evoked cerebral blood flow are extensively used to infer neural activity in the brain with functional magnetic resonance imaging (fMRI). However, the relationship of these hemodynamic changes to neural activity, the pathways by which neural activity controls blood flow, and the interaction between sensory-evoked and spontaneous activity are still poorly understood. To address these questions, we will use 2-photon laser-scanning microscopy (2PLSM) and intrinsic optical signal (IOS) to measure spontaneous and sensory evoked hemodynamics in the somatosensory cortex of awake, head-fixed mice. We will measure the relationship between both sensory evoked and spontaneous neural activity and the subsequent blood flow ('neurovascular coupling'). The signaling pathways that underlying this coupling will be dissected by measuring neural activity and blood flow in transgenic mice lacking muscarinic cholinergic receptors on either blood vessels or cortical neurons. This will allow us to disentangle the direct vasodilatory effects of acetylcholine from the indirect effects mediated via increases in neural excitability. Finally, we will determine how sensory evoked activity interacts with ongoing spontaneous activity in the brain. Quantifying how spontaneous and sensory-evoked neural activity couples to blood flow is critical for understanding the function of the healthy brain.